Effects of livestock breed and grazing intensity on grazing systems: 3. Effects on diversity of vegetation

Abstract

Finding an optimal balance between livestock production and grazing impact on plant biodiversity is an important issue in the design of grazing systems. This paper describes a study of the effect of two levels of grazing intensity combined with different animal breeds on plant biodiversity and sward structural diversity of semi-natural grasslands conducted over 3 years in the United Kingdom (UK), France (F), Germany (D) and Italy (I). There were three treatments at each site: moderate grazing intensity with a commercial breed (MC), lenient grazing intensity with a commercial breed (LC) and lenient grazing intensity with a traditional breed (LT). Grazing livestock were cattle in the UK, F and D, and sheep in I. Only grazing intensity had clear effects on vegetation diversity, the effects depending on site-specific vegetation characteristics. In more diverse pastures with finer scale heterogeneity in F and I, there was little effect of the treatments. In less diverse swards with higher grass dominance and coarse-scale heterogeneity, the number of species decreased from initial levels on the lenient grazing intensity treatments (treatments LC and LT), because of increased dominance of grasses reducing the cover of other species, particularly legumes. The structural diversity of the pastures was more affected by level of grazing intensity than botanical diversity. In more diverse, semi-natural grasslands, structural heterogeneity was not affected by the treatments. In less diverse, more productive swards, structural heterogeneity decreased where large patches were initially found on the UK site, and increased where smaller patches were initially found on the D site. It is concluded that management systems to conserve diversity need to consider carefully the background environment, and that more knowledge of the mechanisms involved is needed at farm and landscape scales.

How do sheep affect plant communities and arthropod populations in temperate grasslands?

“…After a change in grazing intensity, species abundance changes more rapidly than plant species richness (Marriott et al, 2002;Louault et al, 2005;Scimone et al, 2007). However, we could not find any global effect of stocking rate on the Shannon index (F 1.30 5 0.06; P 5 0.81; Figure 3) or other indicators of plant community evenness (log normal diversity index: Bullock et al, 2001; Simpson dominance index: Scimone et al, 2007).…”

“…In upper alpine grasslands, stress-tolerant species, plants with low nutritive value and mosses declined after sheep exclusion (Mayer et al, 2009). In contrast to abandonment, reported changes in species composition were much slower when stocking rate was manipulated (Hulme et al, 1999;Marriott et al, 2004;Scimone et al, 2007). This was, for example, the case over the first 5 years of measurements in extensively used ryegrass/white clover sown swards (Marriott et al, 2002), although this last survey did find long-term patterns with A. capillaris, Poa trivialis, Festuca rubra and Holcus lanatus being favored by a reduction in stocking rate, whereas more competitive or ruderal species such as T. repens and Poa annua increased with increasing stocking rate (Marriott et al, 2009).…”

Organic Livestock Farming — Challenges, Perspectives, and Strategies to Increase Its Contribution to the Agrifood System’s Sustainability — A Review

“…Due to this, [24] and [63] highlighted the necessity to deeply study the interactions and effects of the different livestock systems, especially those with beef cattle, since the scientific literature in addressing this sector is scarce. In line with this argument, [64] mentioned that agricultural practices affect biodiversity in a higher degree than the breeds itself.…”

Grassland systems of red meat production: integration between biodiversity, plant nutrient utilisation, greenhouse gas emissions and meat nutritional quality

“…However, in trials across Europe (United Kingdom, Italy, France and Germany) moderate or light grazing of mixed extensive pastures using traditional and commercial breeds of cattle and sheep, gave no consistent live weight gain response and there was no advantage of traditional breeds over commercial breeds (Isselstein et al, 2007). Grazing intensity affected the vegetation diversity but in a site-specific fashion, as dictated by the initial vegetation (Scimone et al, 2007). Large impacts on invertebrate and bird species can arise from small changes in vegetation.…”